19
\$\begingroup\$

I found a component attached to a PCB inside one of my old $5 devices. There are pink, rubbery things attached to either side of the LCD that can bend and were firmly attached (glued?), and there are a lot of exposed conductive traces where the pink things were attached on the PCB.

I would like to know what these pink things are. Pictures are shown below.

LCD

The front side of the LCD ^

LCD

The back side of the LCD ^

PCB

The front side of the PCB. This is where the LCD is connected to. ^

PCB

The back side of the PCB ^

Again, I would like to know what the pink things are.

\$\endgroup\$

2 Answers 2

Reset to default
28
\$\begingroup\$

Often called Zebra strips (or Elastomeric connectors). They have very thin vertical conductors that connect between flat PCB pads and things like LCD pads on glass.

Here is a link with a similar pink component.

http://en.wikipedia.org/wiki/Elastomeric_connector

\$\endgroup\$
3
  • \$\begingroup\$ The picture is exactly the same as what I have! \$\endgroup\$
    – nimsson
    Commented Mar 1, 2015 at 18:35
  • \$\begingroup\$ One a typical hobbyist would use! According to the Ahmed clock hoaxer! \$\endgroup\$
    – Bradman175
    Commented Nov 17, 2016 at 8:24
  • \$\begingroup\$ A super tuto to repair the transparent conductive tape with the black conductive strip on the last picture youtube.com/… \$\endgroup\$
    – JinSnow
    Commented Oct 24, 2022 at 18:45
17
\$\begingroup\$

As others note it's a "zebra connector" which conducts through the plane of the rubber but not across it (ie in the directions you'd expect for it to work).

The 'pitch' of the band s of conduction/non conduction are finer than the pitch of the contacts concerned so that short circuits are not formed between the contacts when the strip is moved "sideways".

Use an Ohm meter to measure resistance through the rubber between directly opposite points and then between points which are offset.
You will find that

  • When the probes are opposite each other there will be a low resistance path between them.

  • When the probes are offset by more than the thickness of the conductive bands that the resistance will be very high (or more :-) ).

This method allows ease of assembly, self alignment of the "connecter" - as long as the LCD contacts and PCB contacts are aligned the rubber strip alignment is non-crucial.

Zebra strip inter-stripe pitch too large - shorting can occur

█ = contact
▓ = zebra strip conductor
░ = zebra strip insulator

Alignment OK:

████  ████  ████  ████     
▓▓▓▓░░▓▓▓▓░░▓▓▓▓░░▓▓▓▓░  
████  ████  ████  ████

misaligned - shorts occur

████  ████  ████  ████      
▓░░▓▓▓▓░░▓▓▓▓░░▓▓▓▓░░▓▓▓  
████  ████  ████  ████

Zebra strip inter-stripe pitch small wrt conductor pitch - shorting can not occur

Alignment OK:

████  ████  ████  ████  
▓░▓░▓░▓░▓░▓░▓░▓░▓░▓░▓░▓    
████  ████  ████  ████

misaligned - shorting still cannot occur

████  ████  ████  ████
░▓░▓░▓░▓░▓░▓░▓░▓░▓░▓░▓░▓    
████  ████  ████  ████

See also this answer

\$\endgroup\$
5
  • 6
    \$\begingroup\$ I tried replacing ASCII-art with UTF8-art, slight improvement? \$\endgroup\$
    – RedGrittyBrick
    Commented Nov 17, 2016 at 16:50
  • 1
    \$\begingroup\$ @RedGrittyBrick, nice work. It's like going back to 1981 and squinting at a monochrome TV from 6 inches away. Love it. \$\endgroup\$
    – user98663
    Commented Nov 17, 2016 at 22:27
  • 1
    \$\begingroup\$ To add another layer of coolness, there's actually glue that does the same thing. Similar principle too. Glue your contacts and FFC together and you got ultralow profile solid connection with no soldering or connector necessary. \$\endgroup\$
    – Barleyman
    Commented Nov 18, 2016 at 12:11
  • 1
    \$\begingroup\$ Interesting @Barleyman. Can you provide a link to one of glues? \$\endgroup\$
    – Jeromy Adofo
    Commented Jun 1, 2020 at 0:05
  • 1
    \$\begingroup\$ @JeromyAdofo They are called "Anisotropic conductive adhesive", Anisotropic conductive film or Z-axis conductive adhesive. Mostly it's supplied as a tape to make application easier but you can buy liquid glue as well, which would be anisotropic conductive paste. \$\endgroup\$
    – Barleyman
    Commented Jun 3, 2020 at 10:32

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.